Quick update...
Not a total waste of time. The tyres seem a tad more pliable on the walls, they now have a slight glossy finish (no dry crust) and they popped on the rim nice and easy lol. It wasn’t the miracle cure I was hoping for but the tyres look better than before they were scrubbed and silicone sprayed. They were going to be binned but now they are being used on a bike and holding pressure with no issues yet. I hope it stays that way when they are rode a little.